TY - JOUR T1 - Antiproliferative Effects of Gefitinib are Associated with Suppression of E2F-1 Expression and Telomerase Activity JF - Anticancer Research JO - Anticancer Res SP - 3387 LP - 3391 VL - 26 IS - 5A AU - MITSUHIRO SUENAGA AU - AKIHIKO YAMAGUCHI AU - HIROSHI SODA AU - KOJI ORIHARA AU - YUICHI TOKITO AU - YOSHIMUNE SAKAKI AU - MEGUMI UMEHARA AU - KENJI TERASHI AU - NAKAAKI KAWAMATA AU - MIKIO OKA AU - SHIGERU KOHNO AU - CHUWA TEI Y1 - 2006/09/01 UR - http://ar.iiarjournals.org/content/26/5A/3387.abstract N2 - Background: Gefitinib (Iressa, ZD1839) is a selective epidermal growth factor receptor tyrosine kinase inhibitor. E2F-1 is a critical determinant in cell cycle. Growth signals up-regulate telomerase activity. The effects of gefitinib on E2F-1 and telomerase in A549, H23 and A431 cells were examined. Materials and Methods: Cell proliferation and cell cycle progression were measured by the WST-1 assay and flow cytometry. The expression of E2F-1 and cyclin-dependent kinase inhibitors was evaluated, and hTERT mRNA expression and telomerase activity were analyzed. Results: In the A431 and A549 cells, treatment with gefitinib inhibited cell proliferation and was associated with an increase in G1-phase. In both cell types, gefitinib decreased the expression of E2F-1 mRNA and protein, followed by the suppression of hTERT mRNA and telomerase activity. In the H23 cells, gefitinib did not affect cell proliferation. Conclusion: The antiproliferative effects of gefitinib may be, at least in part, due to the inhibition of E2F-1 expression and telomerase activity. Copyright© 2006 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved ER -